An embroidery sewing machine is conventionally provided with an X-directional drive mechanism and a Y-directional drive mechanism that transfer a workpiece-holding embroidery frame in two predetermined directions. When sewing various embroidery patterns on a front face of caps or cylindrical fabric such as sleeves of clothing, such embroidery sewing machine is provided with a cap frame unit or a cylindrical frame unit instead of the embroidery frame.
A cylindrical frame unit (cap frame unit) generally has a body frame connected to the Y-directional drive mechanism and a cylindrical rotary frame pivoted rotatably on the body frame. The body frame is driven in the direction parallel to the cylinder bed of the embroidery sewing machine by the Y-directional drive mechanism; whereas the rotary frame is driven by a rotary mechanism connected to the X-direction drive mechanism. The rotary frame allows attachable/detachable attachment of the workpiece-holding cylindrical frame (cap frame).
When mounting the cylindrical frame unit on the embroidery sewing machine, a regulating element is required for supporting the rotary frame on the upper surface side of the cylinder bed of the embroidery sewing machine in order to maintain the rotary frame and the cylindrical frame in their proper positions. It is also desirable for the mounting position of the rotary frame to be vertically adjustable relative to the cylinder bed to absorb differences such as dimensional variance of parts used.
In view of the above requirements, a position regulating mechanism disclosed in JP 2005-76137 A (patent document 1) is provided with a position adjustment element that is supported vertically movably by the body frame. The position adjustment mechanism restricts the rotary frame in its proper position relative to the cylinder bed. More specifically, a protruding wall of the body frame that upwardly protrudes above the rotary frame has a long hole defined for insertion of a fastener bolt. The position adjustment element is fastened to the protruding wall by the fastener bolt inserted in the long hole so as to allow vertical adjustment of its positioning relative to the body frame. When adjusting the position of the rotary frame, the fastener bolt is loosened to lower the position adjustment element relative to the body frame. Thus, a sliding element fixed on the lower end of the position adjustment element applies pressure on the upper surface of the cylinder bed, and the reaction of the pressure regulates the body frame and the rotary frame in its proper upright position.
The cap frame unit disclosed in JP 2005-73813 A (hereinafter referred to as patent document 2) on the other hand, has a position adjustment element closely resembling the counterpart disclosure of patent document 1, and is supported vertically movably by the body frame. Further, a position regulating element abutting the upper surface of the cylinder bed is disposed across a left and right pair of Y-directional connections provided at the rear end of the body frame. The body frame is regulated at a predetermined mount position by the sliding element of the position adjustment element and the position regulating element.
The cap frame units disclosed in patent documents 1 and 2 respectively is mounted on the embroidery sewing machine with the underside of its sliding element placed in abutment with the upper surface of the cylinder bed. In order to allow the rotary frame to rotate smoothly at the upper inner cylindrical surface without contacting the cylinder bed, a small predetermined spacing is required between the upper surface of the cylinder bed and the upper inner cylindrical surface of the rotary frame.
In order to secure such small predetermined spacing, the user was required to hold an integrated assembly of the body frame and the rotary frame on one hand, and insert a thickness gauge of a predetermined thickness between the cylinder bed upper surface and the upper inner cylindrical surface of the rotary frame with the other hand. When a thickness gauge was not available, the user was required to determine the vertical positioning of the rotary frame by visual measurement and fasten the position adjustment element with a bolt, making the positioning of the rotary frame a troublesome task. As described above, obtaining a predetermined small spacing between the cylinder bed upper surface and the upper inner cylindrical surface of the rotary frame is troublesome and complex.